Re: [Asrg] Some data on the validity of MAIL FROM addresses

[Yakov Shafranovich <[e-mail]>]

At 01:34 PM 5/20/2003 +0100, Jon Kyme wrote:

> >Folks, the email operations world has increasingly moved away from
> >real-time processing of SMTP data.
> >
>
>A colleague has just drawn my attention to the relevant part of rfc2505
>(BCP 30) - for completeness here it is:
>
><quote>
>1.5. Where to block spam, in SMTP, in RFC822 or in the UA
>
>    Our basic assumption is that refuse/accept is handled at the SMTP
>    layer and that an MTA that decides to refuse a message should do so
>    while still in the SMTP dialogue. First, this means that we do not
>    have to store a copy of a message we later decide to refuse and
>    second, our responsibility for that message is low or none - since we
>    have not yet read it in, we leave it to the sender to handle the
>    error.
>
></quote>

See RFC 2821, section 3.1.:

---snip----
    However, in practice, some servers do not perform recipient
    verification until after the message text is received.  These servers
    SHOULD treat a failure for one or more recipients as a "subsequent
    failure" and return a mail message as discussed in section 6.
---snip----

Even thought it might be recommended to do processing in real-time, in 
practice many systems do not and will not. We must be take that into account. 

_______________________________________________
Asrg mailing list
[e-mail]
https://www1.ietf.org/mailman/listinfo/asrg